Suppose that a substance in a beaker is heated over a burner in a science lab. Which observation would most likely indicate that a chemical change has occurred in the substance?
1) If the substance is a liquid or solid, an increase in temperature would indicate a chemical change.
2) If the substance is a liquid, a change of some of the liquid to gaseous form would indicate a chemical change.
3) If the substance is a solid, a change of some of the solid to liquid form would indicate a chemical change.
4) If the substance is a liquid or solid, the production of an odor would indicate a chemical change.